Menadione, vitamin K3, belongs to the class of lipid-soluble vitamins and lipophilic substances as menadione cause disturbances in the bacterial membrane, resulting in damage to the fundamental elements for the integrity of the membrane, thus allowing increased permeability. Accordingly, the aim of this study was to evaluate in vitro the antibiotic-modifying activity of menadione in multiresistant strains of , and , with a gradual increase in its subinhibitory concentration. In addition, menadione was compared with cholesterol and ergosterol for similarity in mechanism of drug modulatory action. Antibiotic-modifying activity and antibacterial effect were determined by the broth microdilution assay. Menadione, cholesterol and ergosterol showed modulatory activity at clinically relevant concentrations, characterizing them as modifiers of bacterial drug resistance, since they lowered the MIC of the antibiotics tested. This is the first report of the antibacterial activity of menadione and its potentiation of aminoglycosides against multiresistant bacteria.

Chagas disease is caused by Trypanosoma cruzi, being considered a public health problem. An alternative to combat this pathogen is the use of natural products isolated from fruits such as Eugenia uniflora, a plant used by traditional communities as food and medicine due to its antimicrobial and biological activities. Ethanolic extract from E. uniflora was used to evaluate in vitro anti-epimastigote and cytotoxic activity. This is the first record of anti-Trypanosoma activity of E. uniflora, demonstrating that a concentration presenting 50% of activity (EC(50)) was 62.76 μg/mL. Minimum inhibitory concentration (MIC) was ≤ 1024 μg/mL. Our results indicate that E. uniflora could be a source of plant-derived natural products with anti-epimastigote activity with low toxicity.

Astragalus L. is widely distributed throughout the temperate regions of Europe, Asia, and North America. The genus is widely used in folk medicine and in dietary supplements, as well as in cosmetics, teas, coffee, vegetable gums, and as forage for animals.The major phytoconstituents of Astragalus species with beneficial properties are saponins, flavonoids, and polysaccharides. Astragalus extracts and their isolated components exhibited promising in vitro and in vivo biological activities, including antiaging, antiinfective, cytoprotective, antiinflammatory, antioxidant, antitumor, antidiabesity, and immune-enhancing properties. Considering their proven therapeutic potential, the aim of this work is to give a comprehensive summary of the Astragalus spp. and their active components, in an attempt to provide new insight for further clinical development of these xenobiotics. This is the first review that briefly describes their ethnopharmacology, composition, biological, and toxicological properties.

Candidiasis is the most frequent infection by opportunistic fungi such as Candida albicans, Candida tropicalis, and Candida krusei. Ethanol extract from Eugenia uniflora was assayed, for its antifungal activity, either alone or combined with four selected chemotherapeutic antimicrobial agents, including anphotericin B, mebendazole, nistatin, and metronidazole against these strains. The obtained results indicated that the association of the extract of E. uniflora to metronidazole showed a potential antifungal activity against C. tropicalis. However, no synergistic activity against the other strains was observed, as observed when the extract was associated with the other, not enhancing their antifungal activity.

Abstract. Background: This is the first report demonstrating the antibiotic-modifying activity of cholecalciferol. Aim: In this study, cholecalciferol was evaluated against multiresistant strains of Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. Methods: The antibacterial and modulatory effects of cholecalciferol, ergosterol, and cholesterol (8–512 μg/mL) were evaluated by microdilution assay against multiresistant bacterial strains. Results: Cholecalciferol, when combined with aminoglycosides, was more effective against P. aeruginosa, reducing the concentration of amikacin and gentamicin necessary to inhibit bacterial growth from 156.25 to 39.06 μg/mL and from 39.06 to 9.76 μg/mL, respectively. It is possible that cholecalciferol, due to its lipid-soluble nature, had a lipophilic interaction with the cell membrane, enhancing antibiotic uptake. Cholesterol and ergosterol were used to see if the mechanism of action of cholecalciferol was similar to that of these lipid compounds. Ergosterol and cholesterol increased aminoglycoside activity, where the effect was greater with higher subinhibitory concentration of sterol. Conclusions: There is no reported study on the use of cholesterol and ergosterol as modulators of antibiotics or any other drug, making this the first study in this area highlighting the interaction between cholesterol, ergosterol, and cholecalciferol with regard to modifying aminoglycoside activity.